高马赫数涡轮发动机射流预冷特性研究

Mass Injection Pre-Compressor Cooling Characteristics in High Mach Number Turbine Engine

关键词:  预冷涡轮基发动机  预冷段  高温进气  射流预冷  液氧

Key words:  Precooled turbine-based engine  Pre-cooling section  High-temperature inlet air  Mass injection pre-compressor cooling  Liquid oxygen

摘要:

以气液相变冷却机制为切入点，开展高空模拟试验进气预冷段内水-液氧射流冷却的数值分析，考虑真实雾滴颗粒运动的热力现象，基于欧拉-拉格朗日多相流方法解析气液两相热质传输过程，分析水-液氧混合射流对高马赫数涡轮发动机预冷段内流动及换热特性的影响规律。结果表明，水-液氧射流雾化蒸发的效果具有即时性，基于水雾-水蒸汽比热大和汽化焓高的特点，水雾浓度对主流总温降和总压恢复占主导性；而液氧浓度有利于降低湿空气的热流密度。在射流浓度2%~8%时，预冷段总压降系数为0.84%~1.27%，总温降系数为2.15%~15.12%，即温降为12.92~90.89K。为平衡高空高马赫数时冷却水和液氧的需求，需控制水-液氧的射流比例，建议液氧射流量小于60%的总射流浓度。在“40%水~60%液氧”的射流比例时预冷段内流动和传热特性达到局部最优。在发动机物理转速不变时，射流冷却后预冷段内湿空气来流质量流量增幅0.22%~9.39%，其中空气和水蒸汽含量的贡献份额分别约为71.8%和28.2%。因此，射流预冷有利于涡轮发动机在高马赫数时具有更高的加速度。

Abstract:

The mass injection precooled turbine-based engine has an important demand for cooling water and liquid oxygen at high altitude and high Mach number. A numerical analysis of water liquid-oxygen injection cooling was conducted in the pre-cooling section of high-altitude simulation test inlet air， which was based on the gas-liquid phase change cooling mechanism. Considering the thermodynamic phenomenon of the real droplet movement， the flow field characteristics during the heat and mass transfer process of gas-liquid two-phase were analyzed based on the Eulerian-Lagrangian multiphase flow method. The effects of water-liquid mixture injection on the flow and heat transfer characteristics of the pre-cooling section were discussed in a high Mach number turbine engine. Results show that the effect of atomization evaporation of water liquid-oxygen injection is instantaneous. Based on the advantages of large specific heat and vaporization enthalpy of water mist， water injection concentration is dominant to the total temperature drop and total pressure recovery of the mainstream， while liquid oxygen injection concentration is beneficial to reduce the heat flux density of wet air mixture. When the mass injection concentration is in the range of 2%~8%， the total-pressure drop coefficient is 0.84%~1.27%； then， the total-temperature drop coefficient ranges from 2.15%~15.12%， that is， the temperature drop is 12.92~90.89K. To balance the demand of cooling water and liquid oxygen at high Mach number， it is necessary to control the water-liquid oxygen injection ratio. Especially， the mass flow rate of liquid oxygen recommends not to be higher than 60% of the total mass injection concentration. Moreover， the flow and heat transfer characteristics in the pre-cooling section are locally optimal when the mass injection ratio is ‘40% water-60% liquid oxygen’. When the physical speed of the engine remains unchanged， the inflow mass flow rate of wet air mixture increases by 0.22%~9.39% within the precooling section after mass injection pre-compressor cooling. For an increasement in mass flow， the contribution shares of dry air and water vapor are about 71.8% and 28.2%， respectively. Therefore， mass injection pre-compressor cooling is conducive to a higher acceleration of turbine engine at a high Mach number.